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Q1. ATPase enzyme needed for muscle contraction is located in  

• 1) Troponin  
• 2) Actinin  
• 3) Actin  
• 4) Myosin  

Solution

During muscle contraction, hydrolysis of ATP into ADP and inorganic phosphate occurs. The energy released during the process raises the meromyosin head to a high-energy state. The enzyme myosin ATPase catalyses the reaction in the presence of Ca²⁺ and Mg²⁺.      

Q2. Draw a well-labelled diagram of the rib and rib cage.  

Solution

Rib and rib cage:        

Q3. The membranous areas between the cranial bones of the foetal skull are called  

• 1) Foramina  
• 2) Fontanelle  
• 3) Sutures  
• 4) Areolas  

Solution

Fontanelles comprise any of the soft membranous gaps between the incompletely formed cranial bones of a foetus or an infant. They allow for rapid stretching and deformation of the cranium as the brain expands faster than the surrounding bone can grow.  

Q4. Name the embryonic layer from which the muscles originate.

Solution

Mesoderm

Q5. The number of vertebrae present in the cervical, thoracic, lumbar, sacral and coccyx regions, respectively, are

• 1) 5, 12, 7, 1, 1
• 2) 7, 5, 1, 12, 1
• 3) 1, 7, 5, 12, 1
• 4) 12, 7, 5, 1, 1
• 5) 7, 12, 5, 1, 1

Solution

The vertebrae are grouped into five categories: Cervical vertebrae: 7, present in the neck Thoracic vertebrae: 12, present in the upper back Lumbar vertebrae: 5, located in the abdomen Sacral vertebrae: 5, present in the pelvis Coccygeal vertebrae: 4, present in the vestigial tail

Q6. Distinguish between pectoral and pelvic girdles.  

Solution

Pectoral Girdle     Pelvic Girdle     It consists of the scapula and the clavicle.   It consists of the coxal bones made by the fusion of the ilium, ischium and pubis.   It bears the glenoid cavity.   It bears the acetabulum cavity.   The two halves of the pectoral girdle are not joined to each other, but they are joined to the sternum on its either side.   The two halves of the pelvic girdles are joined to each other by the pubic symphysis.      

Q7. Draw the cross-sectional view of a muscle showing muscle fibres and bundles.

Solution

Cross-sectional view of a muscle showing muscle fibres and bundles:  

Q8. Name the vertebra which articulates with the occipital condyles.

Solution

Atlas

Q9. Represent diagrammatically:     Structure of actin filament   Structure of myosin filament  

Solution

a. Structure of actin filament:           b. Structure of myosin filament:        

Q10. How many bones are present in the front part of the skull which protects the facial region?

Solution

14

Q11. Write any two special properties of muscles.

Solution

Extensibility and elasticity

Q12. Describe the synovial joint.  

Solution

The synovial joint is characterised by the synovial cavity filled with the synovial fluid.     The synovial cavity is present between the articulating bones of the joint.     This arrangement and the presence of the lubricating fluid allow considerable movement.     Some examples are the knee joint and the ball and socket joint present between the glenoid cavity and head of the humerus.  

Q13. Give any two examples of the synovial joints.

Solution

Two examples of the synovial joints are Joint between the humerus and the pectoral girdle Knee joint

Q14. Which ions are stored by the sarcoplasmic reticulum in muscles?

Solution

Calcium ions are stored by the sarcoplasmic reticulum in muscles.

Q15. State the important functions of the vertebral column.

Solution

The functions of the vertebral column are as follows: It protects the spinal cord. It supports the head. It serves as the point of attachment for the ribs and the musculature of the back.

Q16. Define locomotion.

Solution

Voluntary movements which bring a change in place or location of the organism are called locomotion.

Q17. In the pelvic girdle of man, A B, C, D and E, respectively, represent              

• 1) A - Ilium, B - Pubis, C - Acetabulum, D - Pubic symphysis, E - Ischium  
• 2) A - Ischium, B - Acetabulum, C - Pubis, D - Ilium, E - Pubic symphysis  
• 3) A - Ilium, B - Acetabulum, C - Pubis, D - Ischium, E - Pubic symphysis  
• 4) A - Pubis, B - Acetabulum, C - Ilium, D - Ischium, E - Pubic symphysis  

Solution

The pelvic girdle is located in the lower part of the trunk. The bones of the pelvic girdle shown in the diagram are     A - Ilium, B - Acetabulum, C - Pubis, D - Ischium, E - Pubic symphysis  

Q18. Name the filaments found arranged parallel in a muscle fibre.

Solution

Myofibrils

Q19. Which bone articulates with the glenoid cavity?

Solution

The head of humerus articulates with the glenoid cavity.

Q20. What is a sarcomere?

Solution

Sarcomere is the functional region of the myofibril between two successive Z lines.

Q21. Distinguish between fibrous joints and cartilaginous joints.

Solution

Fibrous Joints Cartilaginous Joints These joints are immovable joints and do not allow any movement. These joints provide limited movements. The flat bones are fused end-to-end by dense fibrous connective tissues. The bones are joined by the cartilage.  

Q22. Which one of the following is the correct pairing of a body part and the kind of muscle tissue which moves it?  

• 1) Iris - Involuntary smooth muscle  
• 2) Heart wall - Involuntary unstriated muscle  
• 3) Abdominal wall - Skeletal muscle  
• 4) Biceps of upper arm - Smooth muscle fibres  

Solution

Iris - Involuntary smooth muscles     Heart wall - Cardiac muscles     Biceps of upper arm - Striated muscle fibres     Abdominal wall - Smooth muscles  

Q23. Which bone of the axial skeleton is made of 8 bones?

Solution

Cranium

Q24. Name the bones which form the rib cage.

Solution

The thoracic vertebrae, ribs and sternum form the rib cage.

Q25. Explain the structure of the myofibril.  

Solution

Structure of Myofibril:           The myofibril is a unit filament of a muscle fibre.     It is made of two kinds of bands - dark band and light band.     A dark band is also known as an A or anisotropic band (myosin filament) and contains myosin, while the light band is also known as an I or isotropic band (actin filament) and contains actin.     Both the bands or filaments are arranged parallel to each other.     Actin filaments are thinner than myosin filaments and are hence also called thin and thick filaments, respectively.     At the centre of each I band is an elastic fibre called Z-line to which thin filaments are firmly attached.     The thick filaments in the A band are held together by an M line.     The portion of the myofibril between two successive Z lines is considered functional and is called a sarcomere.     In the resting state, the edges of thin filaments partially overlap the free ends of thick filaments on either side leaving the central parts of the thick filament non-overlapped; this is called the H zone.  

Q26. Name the substance which when accumulated in muscles causes fatigue.

Solution

Lactic acid

Q27. Represent diagrammatically the sliding filament theory.  

Solution

Sliding filament theory:        

Q28. What are the bones of the palm called?

Solution

Metacarpals

Q29. Name the muscles present in the inner wall of the reproductive tract.

Solution

Smooth muscles

Q30. State the name for the plasma membrane of the muscle fibre.

Solution

Sarcolemma

Q31. Name the central hollow portion of the vertebra.

Solution

Neural canal

Q32. State the two major divisions of the human skeletal system.

Solution

Two major divisions of the human skeletal system are Axial skeleton Appendicular skeleton

Q33. Name the two bones of the pectoral girdle.

Solution

Scapula and clavicle

Q34. Describe the structure of actin filament.

Solution

The actin filament is made of two polymer F actins which are helically wound to each other. Each F actin is made of a monomer called globular or G actin. Two filaments of a protein called tropomyosin run close to the F actins throughout their length. At regular intervals, a protein named troponin is distributed on the tropomyosin. In the resting phase, the active binding site for myosin present on the actin filament gets masked by the troponin.

Q35. The largest muscle in the human body is  

• 1) Gluteus  
• 2) Stapedius  
• 3) Masseter  
• 4) Sartorius  

Solution

The largest muscle in the human body is gluteus maximus, which is also known as the buttock muscle. It is large because its main function is to keep the body upright.  

Q36. Why are the ribs called bicephalic? What are true ribs?  

Solution

Because the rib bones have two articulation surfaces on the dorsal side, they are called bicephalic.     The first seven pairs of ribs are dorsally attached to the thoracic vertebrae, and they are ventrally connected to the sternum. These ribs are called true ribs.  

Q37. Name the cartilage which helps vertebrochondral ribs to join the seventh rib.

Solution

Hyaline cartilage

Q38. Name the three bones which fuse to form the coxal bone.

Solution

Ilium, ischium and pubis fuse to form the coxal bone of the pelvic girdle.

Q39. Name the three types of muscles based on their location.

Solution

The three types of muscles based on their locations are Cardiac muscles Skeletal muscles Visceral muscles

Q40. Which pairs of ribs are called false ribs? Why?

Solution

The 8^th, 9^th and 10^th pairs of ribs are called false ribs. These three pairs of ribs do not articulate directly with the sternum. Instead they are joined to the 7^th pair by the hyaline cartilage.

Q41. Name the muscle involved in changes of body posture.

Solution

Skeletal muscles

Q42. Explain the following disorders: Osteoporosis Tetany Muscular dystrophy

Solution

Osteoporosis: A decreased level of oestrogen is the common cause. The bone mass is decreased due to which a risk of fracture increases. It usually occurs in old individuals. Tetany: Rapid spasms are experienced in muscles due to a low calcium ion level in body fluids. Muscular dystrophy: It is a genetic disorder. The skeletal muscles degenerate progressively.

Q43. Represent diagrammatically the anatomy of a sarcomere.

Solution

Anatomy of a Sarcomere:  

Q44. Name the muscular disorder which affects the neuromuscular junction or motor-end plate.

Solution

Myasthenia gravis

Q45. Explain the contraction and relaxation of muscles by the sliding filament theory.

Solution

Muscle contraction is initiated by the signal sent by the central neural system to the motor end-plate. As soon as the motor end-plate receives the single, acetylcholine is released at the end-plate which sets the action potential in the sarcolemma. As the action potential spreads through the fibre, it causes the sarcoplasm to release calcium ions. Increase in the calcium level results in binding of calcium with the troponin present on the actin filament. The binding of calcium with the troponin unmasks the active binding site for myosin which is present on the actin filament. Myosin binds with the active site forming the cross-bridge. The energy required for the binding of myosin is obtained from the hydrolysis of ATP. Formation of the cross-bridge pulls the attached actin filaments towards the centre of the A band, and the Z lines are pulled inwards, resulting in the contraction of the sarcomere. As soon as ADP and iP are formed from ATP, myosin goes back to its relaxed state and the cross-bridge is broken. At some point, calcium ions are pumped back to the sarcoplasmic cisternae, which results in the masking of the active binding sites of myosin, resulting in the relaxation of muscle fibre.

Q46. Represent diagrammatically the various stages of cross-bridge formation in muscles.  

Solution

Stages of cross-bridge formation in muscles:        

Q47. Study the given figure. Identify A, B, C and D. Write the number of bones present in B, C and D.  

Solution

A - Clavicle B - Carpals (8 bones) C - Metacarpals (5 bones) D - Phalanges (14 bones)

Q48. Name the monomer of myosin filament.  

Solution

Meromyosin  

Q49. Name the cells which show amoeboid movement and are found in the human body.  

Solution

Macrophages and leucocytes  

Q50. Name the oxygen-storing pigments of muscles.

Solution

Myoglobin

Q51. Explain the structure of the pectoral girdle.

Solution

The pectoral girdle is made of the scapula and the clavicle. The scapula is a large triangular bone which is located on the dorsal part of the thorax between the second and the seventh ribs. It bears an elevated ridge called the spine which extends as the expanded flat process called the acromion. The clavicle articulates with the acromion. The scapula bears a depression called the glenoid cavity below the acromion. The head of the humerus of the forelimb articulates with the glenoid cavity. The clavicle is a long slender bone with two curvatures. It is also called the collar bone.

Q52. Name the joints which do not allow any movement.

Solution

Fibrous joints

Q53. Name the hormone responsible for osteoporosis.

Solution

Oestrogen

Q54. Represent diagrammatically the pelvic girdle and the bones of the hindlimbs.

Solution

Pelvic girdle and the bones of the hindlimbs:  

Q55. Which cell organelle is abundantly present in aerobic muscles?

Solution

Mitochondrion

Q56. Name the cavity to which the thigh bone articulates.

Solution

Acetabulum

Q57. Distinguish between red and white muscle fibres.

Solution

Red Muscle Fibre White Muscle Fibre Myoglobin content is high. Myoglobin content is low. Contain more number of mitochondria. Contain less number of mitochondria.  

Q58. Name the junction between a motor neuron and a sarcolemma.

Solution

Neuromuscular junction or motor end-plate

Q59. State the different regions of the vertebral column and the number of bones present in each region.

Solution

Regions of the vertebral column Number of bones present Cervical region 7 Thoracic region 12 Lumbar region 5 Sacral region 1, fused Coccygeal region 1, fused  

Q60. Differentiate between skeletal muscles and visceral muscles.

Solution

Skeletal Muscles Visceral Muscles They show the presence of striations and are hence called striated muscles. Striations are absent, and they are hence called smooth muscles. Activities are under the control of the nervous system; hence, they are voluntary muscles. Their activities are not under the control of the nervous system; hence, they are called involuntary muscles. They are responsible for locomotory actions and body posture. They are responsible for the movement of food through the digestive tract or the movement of gametes in the genital tract.  

Q61. Which parts of myosin filament act as ATPase?

Solution

The globular head of the myosin monomer acts as ATPase.

Q62. What is the technical term used for the knee cap?

Solution

Patella

Q63. Name the tissue which holds all the muscle bundles together in a muscle.  

Solution

Fascia  

Q64. State the symptom of gout.

Solution

Symptom of gout: Inflammation of joints

Q65. Represent diagrammatically the pectoral girdle and the bones of the forelimbs.

Solution

Pectoral girdle and the bones of the forelimbs:  

Q66. Describe the structure of myosin as a contractile protein.  

Solution

Structure of myosin filament:     Each myosin filament is made of monomers of protein called meromyosin.     Each meromyosin has two regions - heavy meromyosin (HMM), which is a globular head with a short arm, and light meromyosin (LMM), which is the tail.     The globular head acts as an active ATPase, and it also has the binding site for actin.     The globular head and the short arm project outwards at a regular distance and angle from each other and from the surface of the myosin filament. This structure is called the cross-arm.  

Q67. Name the neurotransmitter released at the neuromuscular junction.

Solution

Acetylcholine

Q68. Name the two proteins present in the myofilaments of muscles.

Solution

Actin and myosin

Q69. How many bones are present in the human skeletal system?

Solution

206 bones

Q70. Draw a well-labelled diagram of the human skull and label any 10 parts.  

Solution

Human skull:        

Q71. Name the bone present at the base of the buccal cavity.

Solution

Hyoid bone is present at the base of the buccal cavity.